Misc fixes (#8253)

* typo
* unnecessary special case
* tighten typechecking
* mypy 1.4
* handle ast.Str deprecation
* keyring 24.0.0
* use requests.utils.atomic_open directly

poetry is already using requests, and the docstring for requests.utils
indicates that "this module provides utility functions ... that are also
useful for external consumption".

ie there's no reason copy the code, just use it.